A promising treatment for age-related macular degeneration - responsible for up to 50 million cases of blindness worldwide - works by a more general mechanism than had previously been thought, according to a study in Nature. The discovery raises the possibility that the success of the treatment, thought to require highly specific RNA molecules, might, in fact, result from a more generalized immune response to RNA.
Late-stage age-related macular degeneration patients suffer blindness when excess blood vessel cells proliferate in the retina, preventing it from functioning properly. Trial treatments have attempted to prevent this by injecting molecules called small interfering RNAs (siRNAs) into the eye, to bind to and specifically switch off a gene that promotes such cell proliferation.
But in studies on mice, researchers led by Jayakrishna Ambati found that the effect also seems to work with other siRNA molecules that have no complementarity to this gene. This, they suggest, means that the treatment works not by inhibiting expression of a particular gene, but by boosting the immune system to ward off the encroaching cells. This insight may change our understanding of how to tackle age-related blindness.
Jayakrishna Ambati (University of Kentucky, Lexington, KY, USA)
Abstract available online.(C) Nature press release.
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